One person says that the potentil energy of a particular book kept in an almirah is 20 J and the other says it is 30J. Is one of them necessarily wrong?

A book is lifted from the floor and is kept in an almirah. One personn says that the potential energy of the book in increased by 20 J and the other says it is increased by 30 J. Is one of them necessarily wrong?

Consider the two cases: a. A says that the potential energy of a book placed on a shelf is 10J . b. B says that the potential energy of the same book is -10J . Which one of them is wrong? Justify.

The sum of two integers is 20. If one of them is -5 then the other is

The kinetic energy of one gram molecule of a gas at normal temperature and pressure is (R=8.31J//mol-K)

The kinetic energy of one electron is 2.8xx10^(-13) J. What is the de-Broglie wavelength

There are eight persons sitting in the two rows facing each other. In one row, person I, J, K, M are sitting and in other row, persons Q, S, T, U are sitting. Who faces the person U? Statement 1: Q is sitting second to the left of the person U. K and J are immediate neighbours of each other. M is at one of the extreme ends. Statement 2: U is sitting opposite to the person who is second to the left of the person K. I is sitting second to the right of the person J. Q and T are immediate neighbours. Statement 3: K faces Q. T is second to the left of the person S. M is second to the left of person T. S is sitting immediate right of Q

Examine whether the following are polygons. If any one among them is not,say why?